Added fix to resolve datasource when A/B testing with a View Rendering

[lchiao]

This fix corrects the A/B testing in View Renderings.

There was a previous fix made for similar reports to A/B testing, but that only corrected the issue with Controller Renderings.

I encountered this issue as I have a custom object construction task to map a custom view model. I noticed that A/B testing worked fine when Controller Renderings were used, however they broke with View Renderings and the Item was null with GetItemByPathOptions of the datasource in ItemUri format

This should address #433

[muso31]

@mikeedwards83 looks good